life TUESDAY, AUGUST 31, 2010

Three ways to create offspring

By Robin McKie The Guardian Scientists are working on three different techniques for creating offspring from the cells of endangered species.

Nuclear transfer This technology was used to create Dolly the sheep and involves transferring the nucleus of an adult mammal cell into a developing egg cell whose own nucleus has been removed. Scientists have cloned two endangered types of cattle — the gaur and the banteng — this way but have found the technique is associated with early deaths and malformations.

Mixing cells This technique would involve mixing stem cells from an endangered animal with those of a more common, but related species. Offspring from this mix would then be selectively mated to breed out the genes of the common animal and leave only a purebred version of the endangered creature.

Creating sperm and eggs By removing stem cells from an animal, scientists hope that they will one day be able to create sperm and eggs of that species. These could then be used, in a petri dish, to create embryos that could then be implanted in a related species. Zoo aims to save endangered species from extinction

San Diego Zoo began collecting skin samples from rare animals in 1972 in the hope they might be used to protect these endangered species in the future. A breakthrough in stem-cell technology means that day is getting closer by Paul Harris The Guardian, London

he inside of a metal box filled with liquid clear for those trying to save endangered animals. If nitrogen and frozen to minus 173°C is the technology is perfected and induced pluripotent hardly the ideal habitat for a large African stem cell cultures can be established for many of the mammal. But, as a test tube is fished out of species held in the Frozen Zoo, then conservationists of bringing back something that has been extinct for Top: A northern white rhinoceros grazes at San Diego Zoo in San the container amid a billowing cloud of white will not just have to rely on preventing extinction by some 10,000 years? It is intriguing and evocative but it Diego, California. Skin cells from 12 white rhinos and 8,400 other gas, a note written on its side is unequivocal coaxing a few remaining individuals to breed. Instead, plays to human hubris. What’s the motivation? Is this animals are stored at the Frozen Zoo laboratory in the zoo’s Institute about its contents. “This is a northern white rhino,” says cell lines preserved in the Frozen Zoo can be added for personal benefit or society saying: ‘We have arcane for Conservation Research. The hope is that the cells can one day be Tscientist Inbar Ben-Nun as she reads out the label and to the possible gene pool, increasing the chances of powers and the world is our oyster,’” he says. used to create cloned animals and replenish endangered species. holds the freezing vial with thick gloves. healthy reproduction. When it comes to species still on the brink, with Above: Test tubes containing the frozen tissue of endangered animals Ben-Nun is holding no ordinary scientific sample. “If we could use animals that were already dead perhaps just a few individuals left, however, Ryder is are held in stasis at San Diego Zoo’s Frozen Zoo laboratory in San For the frozen cells in that test tube could one day ... to generate sperm and eggs then we can use those insistent that humanity has a duty to save them and Diego, California. photos: Bloomberg give rise to baby northern white rhinos and help save individuals to create greater genetic diversity. I see it as that the Frozen Zoo can play a crucial role. Especially the species from extinction. They would be living being possible. I see no scientific barrier,” Loring says. close to Ryder’s heart is one of the species that Loring preserved and frozen. Ryder, sticking with his belief specimens of one of the most endangered species It has also raised another prospect among some is working on: the northern white rhino. There are that there is no point in rescuing the already extinct, on Earth, who after a few months would be trotting observers: that of a Jurassic Park scenario. If viable just eight of the animals left alive on Earth and not hopes instead that studying the po’ouli bird’s genes into wildlife parks, and maybe, just maybe, helping cell samples could be harvested from the remains of all of them are viable breeders. But, if Loring’s work will help conservationists prevent other related and repopulate their kind on the African grasslands. No extinct animal species, such as stuffed Tasmanian succeeds in creating northern white rhino induced endangered species from following the same path. wonder that the place where the sample came from is tigers in museums or the woolly mammoth corpses pluripotent stem cells and then turning them into “Maybe we cannot bring back the po’ouli, but we can called the Frozen Zoo. dug up from the Siberian tundra, then perhaps sperm and eggs, that gene pool can be deepened again. use its secrets to help others,” he says. The Frozen Zoo was founded in 1972 at San scientists would one day be able to reverse extinction. It is a race against time. Unlike with the drill Ryder believes the importance of the Frozen Diego Zoo’s Institute for Conservation Research It is not a prospect that many scientists involved want monkey, Loring’s efforts with rhino cells have not yet Zoo cannot be overestimated in the face of the vast as a repository for skin-cell samples from rare and to encourage. But ever since news of Loring’s work worked. But at least Loring thinks she knows why. pressures that humanity is putting on the creatures endangered species. At the time that the first samples with the drill monkey cells was revealed, the Jurassic The drill monkey samples were coaxed into becoming with which it shares the planet. In fact the Frozen were collected and put into deep freeze it was not Park headlines have been coming thick and fast. induced pluripotent stem cells using viruses loaded Zoo’s collection of samples is so valuable that a really known how they would be used and genetic Loring’s lab at Scripps holds samples from the with carefully selected human genes that can trigger secret duplicate collection has been established in technology was in its infancy. But there was a sense northern white rhino and the drill monkey, but the that reaction. Loring suspects it worked with drill case a natural or manmade disaster were to strike the that one day some unknown scientific advance might real Frozen Zoo, just a few kilometers away, is on a monkeys because — as fellow primates — they are original. “No time that people have kept something make use of them and it was better to be safe than much larger scale. Housed in a building inside San genetically close enough to humans for the introduced safe in just one place has it worked. This is a globally sorry. Now, thanks to a team at the nearby Scripps Diego Zoo, its freezers contain samples from 8,400 human genes to work properly. Rhinos, she thinks, important depository and its importance is not going Research Institute, that day has come a lot closer. animals, representing more than 800 species. They may be too distantly related. However, she plans to to decrease. Over time there is going to be a big Genetic scientists at Scripps, working from an include Gobi bears, endangered cattle breeds such try again, this time perhaps using genes from a closer disaster. So we have to insure against that,” he says. anonymous-looking building in a business park in San as gaurs and bantengs, mountain gorillas, pandas, a animal relative to the rhino, the horse. He is also keen on reaching out to other, smaller Diego’s northern suburbs, have succeeded in taking California gray whale and condors. The entire gigantic Ryder makes no secret of how emotionally frozen zoos that exist elsewhere, such as one at the samples of skin cells from the Frozen Zoo and turning menagerie is housed in four deep-freeze tanks, attached he is to saving the northern white rhino Audubon Nature Institute in New Orleans and one them into a culture of special cells known as induced representing a staggeringly important slice of some of while there are still living animals, rather than just at the University of Nottingham. He hopes one day pluripotent stem cells. Stem cells are a sort of all- the world’s most rare wildlife. reviving some later entirely from a test tube. He a global network of frozen zoos will be established purpose building block of life that can then become Oliver Ryder, the geneticist who heads the Frozen recalls witnessing the birth of a female northern white to provide the ultimate insurance policy to carry the any other sort of cell. By creating induced pluripotent Zoo program, welcomes the news of Loring’s work, rhino more than 20 years ago and watching it being Earth’s rarest animal species into the future. “Having stem cells from a species it is now theoretically possible which itself built on a breakthrough in 2007 by Japanese introduced to its herd: something that would be lost a duplicate site is an important step but in the long to use them to create egg cells and sperm cells. Those scientist Shinya Yamanaka. For Ryder it is confirmation for ever if the last northern white rhino died before run we need to have a global network,” he explains. two could then be combined via in vitro fertilization to that the zoo’s founding as a sort of “bet” on the science Loring’s technology is perfected. “I saw her meet the “The future will thank the present generation for form a viable embryo. And long-dead animals whose of the future now has great prospects of paying off. “We rest of the rhino herd. There was a clear sense of saving what we can save. We have to look beyond the species are almost extinct could create new life. The wondered if one day pigs would fly. Well, now pigs are how to meet the baby. If we wait until there are no current moment. People who are not yet born will breakthrough, so far, has come with creating induced flying. I am very excited by the results,” Ryder says. white rhinos and then one is created from a test tube, greatly appreciate what we can do.” pluripotent stem cells for the silver-maned drill monkey, But Ryder does not appreciate some of the to whom are we going to introduce it?” he says. “My That opinion holds true for Loring, too. Her a primate native to just a few parts of West Africa and wilder headlines that have sprung from the potential feelings about the rhino come straight from the heart. success in creating induced pluripotent stem cells which is the continent’s most endangered monkey. On implications of the research. The words “Jurassic I am not ready to give up on this rhino.” has the potential to unlock the whole Frozen Zoo as June 1 this year, the stem cells morphed into brain cells, Park” get short shrift from the plainspoken scientist. Sadly, it is already too late for other species. The a powerful tool for breeding and conservation. She proving their viability. He has little time for those who advocate bringing Frozen Zoo already holds samples from animals is already thinking of getting a third species from the “The Frozen Zoo was a wonderful idea. They just back long-dead species or those fringe figures who that are now extinct. One such is the po’ouli bird, zoo to add to the Scripps research on drill monkeys thought: ‘Well, something might happen, so we should dream one day of recreating a dinosaur just like in a species of honeycreeper that lived in Hawaii and and the northern white rhino. She, too, is seeing the preserve some samples for the future,’” says Jeanne Steven Spielberg’s movie. Apart from the fact that the was only discovered in 1973. Unfortunately, the last big picture and says there is a moral imperative to use Loring, who is leading the Scripps team of which science of extracting viable DNA for such animals is recorded sighting of the po’ouli was in 2004, and it the animals kept in the Frozen Zoo to preserve rare Ben-Nun is a part. “This is the first time that there has virtually impossible, he believes it distracts from the is thought to be extinct, assailed by habitat loss and species as part of a living, breathing global ecosystem. been something that we can do.” Frozen Zoo’s primary aim: to stop species becoming the introduction of disease by humans. Now it resides “The idea of doing it has become a reality,” The implications of Loring’s breakthrough are extinct in the first place. “What would be the benefit only in the Frozen Zoo in the form of its skin cells Loring says.